System of electrical distribution.



'No. 7|4,l54. Patented Nov. 25, I902. A. G. DAVIS.

SYSTEM OF ELECTRICAL DISTRIBUTIDN.

(Application filed June 25, 1897.|

(No Model.) 2 Sheets-$heet l.

NM 0 o I 1 W o o o O O0 0 o wi/bheooe/q aywewboz r v J 4 Patented Nov.25, I902.

A. a; DAVIS. E SYSTEM OF ELECTRICAL DISTRIBUTION.

[Application filed June 25, 1B97.|

2 Sheets-Sheet 2.

(No Modei.)

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wiltvmooao NrrEo STATES PATENT ries.

ALBERT GOULD DAVIS, OF WVASHINGTON, DISTRICT OF COLUMBIA,

ASSIGNOR TO THE GENERAL ELECTRIC COMPANY, A CORPORA- TION OF NEW YORK.

SYSTEM OF ELECTRICAL DISTRIBUTION.

SPECIFICATION forming part 0f Letters Patent No. 714,154, dated November25, 1902.

Application filed June 25, 1897. Serial No. 642,239. (No model.)

To all whom it may concern:

Be it known that LALBERT GOULD DAVIS, a citizen of the United States,residing at IVashington, in the District of Columbia, have inventedcertain newand usefulImprovements -in Systems of ElectricalDistribution, (Case No.8,) ofwhich the followingis a specification.

My invention relates to systems of electrical distribution, and moreparticularly to those systems in which it is desired to supplymultiphase translating devices from single-phase mains, though it isapplicable to any system in which it is desired to increase the numberof phases of an alternating current.

In practicing myinvention I provide a plurality of sources ofelectromotive force, preferably, though not necessarily, counterelectromotive force, dephased from each other by a definite and fixedamount, and I prefer to connect these sources in series across each pairof the mains carrying the current whose number of phases is to beincreased. The electromotive forces of these sources being dephase'dfrom each other form with the electromotive force on the mainsa systemof poly- I phase electromotive forces of an order depending on thenumber of phases of electromotive force of the sources and on the orderof the original system. For example, it is possible to join twoarmatures mechanically or otherwise so that their electromotive forcesare dephased by ninety degrees and to connect them in series across apair of singlephase mains. With this arrangement a twophase system ofcurrents and electromotive forces may be obtained. In a similar mannerit is possible to obtain a three-phase system. In the annexed drawings,which illustrate embodiments of my invention, Figure l is a general Viewof a single-phase system of distribution with means for supplyingtwo-phase currents to a translating device connected thereto. Fig. 2 isa View of a modification, and Figs. 3 and 4 are vector diagrams.

Referring more particularly to Fig. 1, A represents a single-phasegenerator feeding a pair of mains 8 9 through the step-up transformer T.Connected to these mains are other transformers, as T T At thoseportions of the system where single-phase translating devices only aredesired these transformers are connected to a pair of secondary mains inthe usual way. Such an arrangement is illustrated at T*, where lamps Lare shown in multiple with the secondary mains; but at points wheremultiphase currents are desired, as at T, my improved phase-modifier isinserted. It will be seen that the mains 4 and 5, leading from thesecondary winding of T, are connected to the primary windings B B of apair of synchronous dynamo-electric machines connected in series acrossthe lines. These machines are preferably motors, but may, if preferred,receive external power. The secondary members C C of thesemachines,which in the form shown are the directcurrent members, arerigidly coupled together, as by the shaft S,in such a way that theelectrom otive forces or counter electromotive forcesof the two machinesare dephased. \Vhile I have illustrated a rigid mechanical connection, Ido not limit myself thereto, but contemplate using any mechanical orelectrical or other means which will secure the desired result; but I donot desire to include in this specification or in the claims hereto 1annexed any device in which the mutual reactions between threealternating dynamo electric machines connected in series are the onlymeans of securing the desired phase difference, as I am not the inventorthereof. The members C C are shown as excited from the direct-currectexciter E, and their excitation is controlled by the adjustableresistances R R as usual.

In the specific form illustrated the phase angle between theelectromotive forces of the two motors is ninety degrees. Let the vector(2 cl, Fig. 3, represent in magnitude and phase the impressedelectroinotive force at the secondary terminals of T. Let a b and b 0,two vectors such that the angle ab cis ninety degrees, represent theelectromotive force of the two auxiliary machines. Then if the twofield-magnets C C are properly adjusted the Vectors a b and b a willform with their resultant a, c an isosceles right triangle, and theresultant may be made equal in magnirude to the impressed electromotiveforce 6 61 I00 and opposite in phase. Therefore the electro motiveforces a Z), Z) c, and d e are such that two-phase currents flow in thesystem 4 5 6, connected to the outer terminals and to the pointintermediate the windings.

I have shown various translating devices connected with the mains, asmotors M M M M.

M is a three-phase motor fed through the phasing-transformer T. Thisphasing-transformer is of the well-known Scott type and need not beparticularly described herein. M is a two-phase induction-motor of anypreferred type. M is a monocyclic inductionmotor so wound as to takecurrent from the main 6 only when starting, as is well under stood inthe art. A synchronous motor may be used, if preferred, and I have showna monocyclic synchronous motor at M provided with a separate exciter andrheostat.

High-voltage lamps I, may be connected across the mains 4 5, whilelow-voltage lamps L may be inserted, as is usual, in two-phase systems.I have also shown lamps I1 connected direct to the secondary terminalsof the transformer T, where they will not tend to unbalance the system.

As indicated in Fig. 4, the angle between the two auxiliary sources ofelectromotive force may be made one hund red and twenty degrees, when athree-phase system will be formed, the vectors being a b, b c, and cl6'.

It is obvious that by suitably choosing the number and phase angles ofthe auxiliary sources of electromotive force any preferred system may beobtained.

I have shown my improved phase-modifier applied to a single-phasesystem; but it is obvious that it may be applied to any system whatever.Each phase-modifier so applied will serve to increase the number ofphases of electromotive force between the two terminals across which itis connected.

I have illustrated in Fig. 2 another form which my improvedphase-modifier may take. T is a source of electromotive force and may bea transformer connected to a single-phase system at any desired point.:3 B are two angularly-displaced primary windings, preferably on asingle core, connected in series, as shown. C is the secondary member,which may be of any suitable type-as, for example, similar to O or 0,Fig. l. I have, however, shown it as a short-circuited rotor. \Vhen oncestarted, this device will run as a singlephase induction-motor; but thecounter electromotive forces of the two windings B and I3 are dephased,as one winding is in advance of the resultant polar line, while one isbehind it. The dephased counter electromotive forces act as do theelectromotive forces or counter electromotive forces of B and B, Fig. 1,and the wires 4 5 6, connected to the outer and intermediate terminalsof the two windings, form a multiphase system, the phase angles of whichdepend on the angles between the connection E and B In order to startthe armature I have illustrated a condenser K with a suitable switch Sin multiple with one of the inducingwindings, as B .Vhen the switch S isclosed, this condenser tends to advance the current in B with which itis in series, and to lag the current in B with which it is in shunt, anda rotary field is created which causes the armature to start. When aproper speed is attained, the switch S is opened and the machine runs asan induction-motor, as before stated, supplying multiphase currents tothe mains 4 5 6.

I do not claim in this application the novel method herein disclosed,since this method constitutes the subject-matter of a divisionalapplication, Serial No. 103,151, filed April 16, 1902. Neither do Irestrict myself to the various forms shown and described herein, sinceit is obvious that they may be greatly varied without departing from thespirit and scope of my invention.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is

1. In combination, a source of single-phase electromotive force, aplurality of primary windings connected in series with each other andwith said source, said windings being so mounted that they are rigidlymaintained in fixed angular relation to one another, a secondary membercapable of rotation relatively to said windings, and connections leadingfrom said windings to translating devices.

2. In combination, a source of single-phase electromotive force, aplurality of primary windings connected in series with each other andwith said source, said windings being so mounted that they are rigidlymaintained in fixed angular relation to one another, a sec ondary membercapable of rotation relatively to said windings, and connections leadingfrom the terminal and intermediate points of said windings, to a systemof distribution.

The combination of a source of singlephase electromotive force, aplurality of primary windings connected in series with each other andwith said source, the different primary windings being so mounted andarranged that their counter electromotive forces are rigidly maintainedin a dephased relation, a short-circuited member capable of rotationrelatively to said windings, and connections leading from said windingsto translating devices.

at. In combination, a source of single-phase electromotive force, aplurality of angularlydisplaced primary windings connected in serieswith each other and with said source, a secondary member capable ofrotation relatively to said windings, means for starting said secondarymember, and connections leading from said windings to translatingdevices.

5. The combination of a source of singlephase electromotive force, aplurality of primary windings connected in-series with each other andwith said source, the different pri- ICO mary windings being so mountedand arranged that their counter electromotive forces are rigidlymaintained in a dephased relation, a short-circuited secondary membercapable of rotation relatively to said windings, means for starting saidsecondary member, and connections leading from said windings totranslating devices.

6. In combination, a source of electromotive force, a plurality ofwindings connected thereto, means for producing in said windingselectromotive forces of displaced phase, means for maintaining a fixedand definite phase relation between said electromotive forces, andconnections from said windings to translating devices.

7. The combination of a source of electromotive force, as for example asecondary coil of a transformer, a plurality of windings connectedthereto and constituting sources of electromotive forces, means formaintaining a fixed and definite phase relation between theelectromotive forces of said sources, and means whereby the resultantelectromotive forces of the said windings shall be maintained in adefinite phase relation with said source, substantially as described.

8. The combination with a source of singlephase current, of a pluralityof windings, on one or more dynamo-electric machines, connected inseries across the said source, means for producing in said windingselectromotive forces of displaced phase, and mechanical connectionsestablishing a fixed and definite phase relation between theelectromotive forces of the said windings, but leaving the resultant ofsaid electromotive forces free to arrange itself in the proper phasalrelation with the said source.

9. The combination with a source of singlephase current,of a pluralityof windings,upon one or more dynamo-electric machines, connected inseries across the said source, means for producing in said windingselectromotive forces of displaced phase,and mechanical connectionsestablishing a fixed and definite phase relation between theelectromotive forces of said windings, but leaving the resultant of saidelectromotive forces free to arrange itself in the proper phasalrelation with the said sources, and connections from terminal andintermediate points of said windings to a multiphase translating device.

10. In combination,a source of single-phase electomotive force, aplurality of primary windings connected inseries across the source, saidwindings being so mounted that they are rigidly maintained in fixedangular relation to one another, means for generating electomotiveforces of displaced phase in said windings, and connections leadingtherefrom to translating devices.

11. In combination,a source of single-phase electromotive force, aplurality of primary windings connectedin series across the source, saidwindings being so mounted that they are rigidly maintained in fixedangular relation to one another, means for generating electromotiveforces of displaced phase in said windings, and a system of distributionhaving its conductors connected to the terminal and intermediate pointsof said windings.

12. In combination,asource of single-phase electromotive force, aplurality of primary windings connected in series across the source,means for generating electromotive forces of displaced phase in saidwindings, the said windings being so mounted that the electromotiveforces generated therein are rigidly maintained in a definite phaserelation, and connections leading therefrom to translating devices.

13. In combination,a source of single-phase electromotive force, aplurality of primary windings connectedinseriesacross the source, meansfor generating electromotive forces of displaced phase in said windings,the said windings being so mounted that the electromotive forcesgenerated therein are rigidly maintained in a definite phase relation,and a system of distribution having its conductors connected to theterminal and intermediate points of said windings.

Signed at Washington, District of Columbia, this 17th day of June, A. D.1897.

ALBERT GOULD DAVIS.

Witnesses:

W. H. DAVIS, THEO. T. SNELL.

